As power costs continue to rise and environmental impact concerns mount, the demand for power devices with increased performance and efficiency continues to grow. One way to improve the performance and efficiency of a power device is by fabricating the device using silicon carbide (SiC). Power devices made with SiC are expected to show great advantages compared to conventional silicon power devices in switching speed, power handling capability, and temperature handling capability. Specifically, the high critical field and wide band gap of SiC devices allows for increases in both performance and efficiency when compared to conventional silicon devices.
Due to the performance limitations inherent in silicon, a conventional power device may require a bipolar structure, such as that of an insulated gate bipolar transistor (IGBT), when blocking high voltages (e.g., voltages greater than 5 kV). While utilizing a bipolar structure generally decreases the resistance of the drift layer due to conductivity modulation thereof, bipolar structures also suffer from relatively slow switching times. As will be appreciated by those of ordinary skill in the art, the reverse recovery time (attributed to the relatively slow diffusion of minority carriers) of a bipolar structure limits the maximum switching time thereof, thereby making silicon devices generally unsuitable for high voltage and high frequency applications.
Due to the performance enhancements discussed above with respect to SiC power devices, unipolar SiC power devices may be used to block voltages up to 10 kV or more. The majority carrier nature of such unipolar SiC power devices effectively eliminates the reverse recovery time of the device, thereby allowing for very high switching speeds (e.g., less than 100 ns for a double-diffused metal-oxide-semiconductor field-effect transistor (DMOSFET) with a 10 kV blocking capability and a specific on-resistance of about 100 mΩ*cm2).
Power devices are often interconnected and integrated into a power module, which operates to dynamically switch large amounts of power through various components such as motors, inverters, generators, and the like. As discussed above, due to the rising cost of power and environmental impact concerns, there is a continuing need for power modules that are smaller, less expensive to manufacture, and more efficient, while simultaneously providing similar or better performance than their conventional counterparts.